1. The Field of the Invention
The present invention relates to a system for realizing economy of operation of an internal combustion engine and, in particular, to a system for selectively disabling up to half of the cylinders of an operating engine.
2. The Prior Art
It has long been realized that there is the possibility of effecting economy of operation of internal combustion engines by disabling at least a portion of the cylinders when the power afforded by the extra cylinders is not necessary. This type of operation is generally known as split engine operation and is the possibility of effecting economy of operation of internal combustion engines by disabling at least a portion of the cylinders when the power afforded by the extra cylinders is not necessary. This type of operation is generally known as split engine operation and is explained in a basic reference, namely, U.S. Pat. No. 2,954,022. It is noted in the above-mentioned patent that considerable economies can be realized when it is possible to resort to split engine operation, for example, being able to operate an 8-cylinder engine on 4 cylinders under moderate load conditions. The economy is effected by the fact that individual cylinder efficiency is increased when the individual cylinder load is increased during split engine operation in contrast to reduced cylinder loads as occur with full engine operation during light or moderate load conditions.
It is an inherent characteristic of internal combustion engines to be most efficient under high load conditions. This is attributable to the fact that the quantity of the air fed to the cylinders is applied in the maximum amount when the throttle is fully open, indicative of a high load, therefore more air may be compressed, in turn increasing the compression ratio. Since engine efficiency increases with compression pressure, the compression pressure increases with cylinder load, the desirability of split or part cylinder engine operation as a means for maintaining high cylinder loads becomes apparent. However, all previous systems, which have attempted to effect such a split engine operation have been overly complicated.
One attempt to effect economic engine operation by reduction of operating cylinders is disclosed in U.S. Pat. No. 3,874,358 wherein some of the cylinders are fully disabled by being replaced with dummy modules. Thus, the disabled cylinder is not available for re-entry into the system should the operator encounter an emergency situation requiring additional power.
U.S. Pat. No. 2,394,739 disclosed a device for controlling the valve operation in an internal combustion engine to selectively disable cylinders by holding their exhaust valves closed. This type of invention has a definite advantage over the device mentioned in U.S. Pat. No. 3,874,358 since the cylinders are only temporarily disabled and will still be available for use if and when it is necessary.
U.S. Pat. Nos. 2,166,968, 2,875,742, 2,919,686, 2,596,640, and 3,874,358 show representative devices which control the operation of an internal combustion engine by selectively allowing flow of the fuel charge to the cylinders. In each case, when full power is needed, the fuel charge is directed to all of the cylinders. However, when more moderate conditions prevail, the fuel charge is directed to less than the total number of cylinders.